Clutch actuator unit

ABSTRACT

A clutch actuator unit comprises a housing ( 8, 9 ), a screw mechanism and an actuator head which at one end engages the screw mechanism ( 1, 2 ) and at the other end has an actuating end ( 18 ), which actuator head ( 16 ) can be displaced in axial direction by the screw mechanism upon driving the screw mechanism. The actuating end ( 18 ) of the actuator head ( 16 ) is displaceable in transverse direction with respect to the screw mechanism as well.

The invention is related to an actuator for a clutch. Such clutchactuator unit provides a displacement of the lever against the biasingforce of the diaphragm spring of a plate clutch.

The actuator units are generally of a hydraulic type. They are able toactuate the end of the clutch lever, which end carries out anarch-shaped trajectory.

The object of the invention is to provide an actuator unit of this typewhich is of a mechanical nature, so as to i.a. avoid the use ofhydraulic fluids. This object is achieved by means of a clutch actuatorunit comprising a housing, a screw mechanism and an actuator head whichat one end engages the screw mechanism and at the other end has anactuating end, which actuator head can be displaced in axial directionby the screw mechanism upon driving the screw mechanism, the actuatingend of the actuator head being displaceable in transverse direction withrespect to the screw mechanism as well.

The clutch actuator unit according to the invention can be driven by anysuitable motor, in particular by means of an electric motor. In thatcase, a clutch-by-wire system can be applied, wherein electrical wiresare used instead of hydraulic lines.

The transverse moveability of the actuator head can be obtained by meansof a swivel.

In one of the embodiments (the so-called “push” version), the actuatorhead engages the screw of the screw mechanism, said screw beingsupported by a linear guide. The linear guide protects the screw againstthe lateral forces which result in the tilted positions of the swivel.

This lateral support can be obtained in an embodiment wherein the screwand the actuator head are at least partly accommodated within atube-like guiding means or cylinder, a support piston being providedwhich is connected to the screw and which is slidably supported withinsaid cylinder.

A very stable support of the clutch forces is obtained in case theactuator head comprises at least two telescopic parts, one of whichengages the screw mechanism, and the other of which carries theactuating end, biasing means being provided for biasing said telescopicparts away from each other.

Furthermore, the actuator head has one telescopic part which isconstantly urged outwardly. Such constant bias is advantageous in thatthereby the clutch lever is held under a constant preload, and also thebearing which is positioned between said clutch lever and the diaphragmspring. As a result, the occurrence of undesirable noises associatedwith a loosely held bearing are avoided.

Preferably, one of the telescopic parts is a pin, and the other of thetelescopic parts comprises a sleeve having a bore in which the pin isslidingly accommodated, a biasing spring being provided which engagesboth the pin and the sleeve. Said spring rests against the supportpiston and against an outwardly extending flange of the sleeve, saidflange fitting with play within the bore so as to allow transversemovement of the actuator head.

The cylinder, at its end facing away from the actuator head, has aninwardly protruding flange supporting a bearing which carries therotatable nut of the screw mechanism.

The clutch actuator unit according to the invention can be carried outfor exerting a pushing and/or a pulling force on the object to beactuated. In the case of a “pulling” embodiment, for instance a cableconnection may be applied between the screw mechanism and the actuatorarm.

Furthermore, the housing may be mounted in such a way that it can swivelso as to additionally allow the screw mechanism to follow objectmovements.

The spring for preloading the unit may also be applied externally.

The invention will now be described further with reference to the “pushversion” embodiment shown in the drawings.

FIG. 1 shows a cross section through a first embodiment, of clutchactuator unit according to the invention, in retracted position.

FIG. 2 shows the embodiment according to FIG. 1 in extended andswivelled position.

FIG. 3 shows the modular layout of the embodiment according to FIGS. 1and 2.

The clutch actuator unit according to the invention as shown in theFIGS. 1-3 comprises a nut 1 and a screw 2 which have screw threads whichengage each other by means of balls 29. The nut 1 is rotatably supportedby means of the angular contact ball bearing 27, the inner ring of whichis integrated with the nut 1.

The outer ring of the bearing 27 is accommodated in a cylinder 20, andrests against the inwardly pointing flange 26 thereof.

The cylinder 20 itself is accommodated in the housing 8, 9 of the clutchactuator unit.

The housing contains an electric motor 14, the rotor 28 of which isconnected to a sleeve. This sleeve is at one end connected to the nut 1,and at the other end is supported by means of the ball swivel 10, 11, 12which rests against the housing cover 9.

The screw 2 is held against rotation, and engages an actuator head 16which by means of a swivel end 17 engages the swivel support 19 which iscarried out as a ball. This swivel support 19 is connected to the screw2.

The actuator head 16 also has an actuating end 18, which for instancecan be connected to the clutch lever.

The actuator head 16 (which may consist of plastic) comprises twotelescopic parts, carried out as a sleeve 22 in the bore 23 of which thepin 21 is accommodated. The sleeve 22 has an outwardly extending flange24, a compression spring acting between the flange 24 and the bottom ofa guidance piston 3. The guidance piston 3 is slideably accommodatedwithin the cylinder 20. This sliding piston 3 is connected to the screw2, and supports this screw against any lateral forces which may beexerted on the swivel support 19 thereof when the actuator head 16 isswivelled out of its aligned position.

As shown in FIG. 2, the actuator head 16 may swivel from its alignedposition to an oblique position, e.g. so as to follow the curvedmovement of the arch-shaped movement of the clutch lever end.

Moreover, the sleeve type telescopic part 22 has been driven to theoutside under the influence of the compression spring 5. As a result ofthe pressing force provided by this compression spring 5, the actuatingend 18 of the actuator head 16 is constantly urged against the clutchlever, thus providing a preload on the bearing which usually isavailable between the clutch lever and the diaphragm spring.

FIG. 3 shows that the clutch actuator unit has a modular layout. Thescrew mechanism 2, 1 and the actuator head 16 together with the angularcontact ball bearing 27 are accommodated within the module 30. Theremaining components, that is the motor 14, the support bearing 10-12,and the sleeve 15 are accommodated within the other module 31. By meansof the flanges 32, 33 these modules 30, 31 can be attached to eachother.

At least one of the components of the clutch actuator 4 may bemanufactured by means of powder metallurgy. Also, a hard whirlingoperation may be applied for manufacturing the actuator components.

1. Clutch actuator unit, comprising a housing, a screw mechanism and anactuator head which at one end engages the screw mechanism and at theother end has an actuating end, which actuator head can be displaced inaxial direction by the screw mechanism upon driving the screw mechanism,the actuating end of the actuator head being displaceable in transversedirection with respect to the screw mechanism as well.
 2. Clutchactuator unit according to claim 1, wherein the actuator head engagesthe screw mechanism through a swivel.
 3. Clutch actuator unit accordingto claim 1, wherein the actuator head engages a screw of the screwmechanism, said screw being supported by a linear guide.
 4. Clutchactuator unit according to claim 3, wherein the screw and the actuatorhead are at least partly accommodated within a tube-like guiding meansor cylinder, wherein the linear guide a support piston which isconnected to the screw and which is slidably supported within saidcylinder.
 5. Clutch actuator unit according to claim 1, wherein theactuator head comprises at least two telescopic parts, one of whichengages the screw mechanism, and the other of which carries theactuating end, biasing means being provided for biasing said telescopicparts away from each other.
 6. Clutch actuator unit according to claim5, wherein one of the telescopic parts is a pin, and the other of thetelescopic parts comprises a sleeve having a bore in which the pin isslidingly accommodated, wherein the biasing means includes a biasingspring which engages both the pin and the sleeve.
 7. Clutch actuatorunit according to claim 6, wherein the biasing spring rests against thesupport piston and against an outwardly extending flange of the sleeve,said flange fitting with play within the bore so as to allow transversemovement of the actuator head.
 8. Clutch actuator unit according toclaim 7, wherein the cylinder comprises an abutment for limiting amaximum mutual stroke of the telescopic parts.
 9. Clutch actuatoraccording to claim 5, wherein one telescopic part engages a screw of thescrew mechanism through a push/pull swivel connection.
 10. Clutchactuator unit according to claim 4, wherein the cylinder, at its endfacing away from the actuator head, has an inwardly protruding flangesupporting a bearing which carries a rotatable nut of the screwmechanism.
 11. Clutch actuator unit according to claim 1, furthercomprising a support bearing associated with the screw mechanism,wherein the support bearing is a ball bearing.
 12. Clutch actuator unitaccording to claim 1, wherein the screw mechanism comprises a ball screwwith a lead angle providing back driveability.
 13. Clutch actuator unitaccording claim 1, wherein the screw mechanism comprises a roller screw.14. Clutch actuator unit according to claim 1, wherein the screwmechanism is driveable through an electric motor.
 15. Clutch actuatorunit according to claim 1, wherein a rotor of a motor is connected to anut of the screw mechanism.
 16. Clutch actuator unit according to claim1, wherein an end of a rotor which is facing away from the actuator headis supported with respect to the housing by means of a pivot or bearing.17. Clutch actuator unit according to claim 16, wherein the spring islocated between the screw and the pivot or bearing.
 18. Clutch actuatorunit according to claim 1, wherein a through-going bore is provided,which extends through the screw mechanism, the housing and possibly theactuator head.
 19. Clutch actuator unit according to claim 11, whereinthe ball bearing is a deep groove ball bearing or an angular contactball bearing.